Leetcode 15 3Sum

Given an array S of n integers, are there elements a, b, c in S such that a + b + c =
0? Find all unique triplets in the array which gives the sum of zero.

Note: The solution set must not contain duplicate triplets.

For example, given array S = [-1, 0, 1, 2, -1, -4],

A solution set is:
[
[-1, 0, 1],
[-1, -1, 2]
]

要怎么解决重复是一个问题

万能的sort就起作用了

public class Solution {
public List<List<Integer>> threeSum(int[] nums) {
List<List<Integer>> result = new ArrayList<>();
Arrays.sort(nums);
for (int i = 0; i + 2 < nums.length; i++) {
if (i > 0 && nums[i] == nums[i - 1]) {
continue;
}
int j = i + 1, k = nums.length - 1;

while (j < k) {
if (nums[j] + nums[k] + nums[i] == 0) {
result.add(Arrays.asList(nums[i], nums[j], nums[k]));
j++;
k--;
while (j < k && nums[j] == nums[j - 1]){
j++;
}
while (j < k && nums[k] == nums[k + 1]){
k--;
}
} else if (nums[j] + nums[k] > -nums[i]) {
k--;
} else {
j++;
}
}
}
return result;
}
}